1. Field of the Invention
The present invention relates to a radiation image storage panel.
2. Description of the Prior Art
For obtaining a radiation image, there has been conventionally employed a radiography utilizing a combination of a radiographic film having an emulsion layer containing a photosensitive silver salt material and an intensifying screen. As a method replacing the conventional radiography, a radiation image recording and reproducing method utilizing a stimulable phosphor as described, for example, in U.S. Pat. No. 4,239,968, has been recently paid much attention. In the radiation image recording and reproducing method, a radiation image storage panel comprising a stimulable phosphor (i.e., a stimulable phosphor sheet) is used, and the method involves steps of causing the stimulable phosphor of the panel to absorb a radiation energy having passed through an object or having radiated from an object; sequentially exciting the stimulable phosphor with an electromagnetic wave such as visible light and infrared rays (hereinafter referred to as "stimulating rays") to release the radiation energy stored in the phosphor as light emission (stimulated emission); photoelectrically detecting the emitted light to obtain electric signals; and reproducing the radiation image of the object as visible image from the electric signals.
In the radiation image recording and reproducing method, a radiation image is obtainable with a sufficient amount of information by applying a radiation to an object at considerably smaller dose, as compared with the conventional radiography. Accordingly, this method is of great value especially when the method is used for medical diagnosis.
The radiation image storage panel employed in the radiation image recording and reproducing method has a basic structure comprising a support and a phosphor layer provided on one surface of the support. Further, a transparent film is generally provided on the free surface (surface not facing the support) of the phosphor layer to keep the phosphor layer from chemical deterioration or physical shock.
When the radiation image recording and reproducing method is practically carried out, the radiation image storage panel is repeatedly used in a cyclic procedure comprising steps of exposing the panel to a radiation (i.e., recording a radiation image), irradiating the panel with stimulating rays (i.e., reading out the recorded radiation image), and exposing the panel to light for erasure (i.e., erasing the remaining energy from the panel). In the cyclic procedure, the panel is transferred from a step to the subsequent step to be processed through a transfer system which includes means for holding a panel such as nip rolls.
There is a problem that mechanical shocks attack the side surfaces or edges of the panel through the transfer system so that the panel is apt to suffer abrasion, damages or stripping.
To improve the mechanical strength of the radiation image storage panel in the transfer system, a panel whose side surfaces are covered with a polymer material (and reinforced therewith) has been proposed, as disclosed in Japanese Patent Provisional Publication No. 58(1983)-68746 (corresponding to U.S. patent application Ser. No. 434,885). Since the side surfaces of the panel are covered with the polymer material composed of polyurethane or an acrylic resin, the panel is enhanced in the mechanical strength against the shocks and bending in the transfer system and prevented from the separation between the protective film and the phosphor layer thereof.
The environmental condition in the use of the radiation image storage panel tends to become severer and the radiation image recording and reproducing method requires the more improvement of the durability thereof. It is desired to enhance the resistance to shock of the panel as much as possible by using a polymer having a high adhesion with the panel and a suitable rigidity as the covering material for reinforcing the side surfaces thereof, and to further improve the durability of the panel.